Not sure whether this is a correct subforum to post. Sorry if am wrong

I need advice on designing or more accurately improvising a brown fat activation study. We plan to recruit volunteers who will be subjected to low temp exposure, <20'C for 3hrs followed by PET-CT Scan. Core body temperature is measured via equivital sensor (consumed)

The issue is that our hospital facility does not have an appropriate cold room. The available room next to the ct scan facility has non adjustable central aircon, no window and solid door with no hole. Initially we plan to use portable aircon and lower the temp to 18 but it is not possible without any outlet for hot air.

Any idea on how to around this? Moving room is not an option.Another idea we thought of is cooling vest but have yet to try as they are relatively expensive and may not work.

Would appreciate it if anyone could share their exp on similar study. thank you!